Question: Omar is 5 times as old as Umaima and is also 20 years older than Umaima. How old is Umaima?
Explanation: We can use the given information to write down two equations that describe the ages of Omar and Umaima. Let Omar's current age be $o$ and Umaima's current age be $u$ $o = 5u$ $o = u + 20$ Now we have two independent equations, and we can solve for our two unknowns. Since we are looking for $u$ , and both of our equations have $o$ alone on one side, this is a convenient time to use elimination. Subtracting the second equation from the first equation, we get: $0 =$ $5u$ $-$ $ (u + 20)$ which combines the information about $u$ from both of our original equations. Solving for $u$ , we get: $4 u = 20$ $u = 5$.